Extreme pressure lubricant



States EXTREME PRESSURE LUBRICANT Morton Fainman, Chicago, Ill., assignor to Standard Oil Company, Chicago, 10., a corporation of Indiana No Drawing. Application August 31, 1954, Serial No. 453,436

6 Claims. (Cl. 252-336) extreme pressure characteristics of such lubricants. Such research has been directed primarily to the discovery of new sulfur-containing and/or chlorine-containing compounds which would yield their chlorine and sulfur readily enough to exhibit improved extreme pressure characteristics, yet not to cause undue corrosion. Despite the large sums expended on research and the vast amount 'of time involved in investigating the effectiveness of the many sulfur-containing and chlorine-containing organic compounds the art has not discovered any truly outstanding additives of these types which are widely accepted. Consequently, a desirable approach to the problem is an additive which will increase the effectiveness of lubricants containing lead, sulfur, and chlorine organic compounds. It is therefore an object of this invention to provide an improved extreme pressure lubricant which will give superior lubrication to bearing surfaces which are subjected to high pressures and/ or high rubbing velocities particularly prevalent in the field of automotive application such as hypoid gears and rear axles. Another object of the invention is to augment the extreme pressure efiiciency of lubricants to meet the demands of lubrication of metal to metal contact subjected to ever-increasing pressures at surfacesof such contact. Still another object of the invention is to augment the extreme pressure properties of an oil containing as additives an organic compound such as a lead soap, a sulfurized fatty oil such as sulfurized sperm oil and chlorinated hydrocarbons.

I have! found that the extreme pressure, that is, E. P. properties of leadand sulfur-containing organic compound additives which are used in conjunction with chlorinated hydrocarbons additives to improve the load-carrying properties of lubricating oils can be greatly enhanced by the incorporation in said oil of a chlorinated fatty acid corresponding to the general formula CnHZn-xClnOZ where n is an integer of value from 12 to 30 and x is an integer of value from 1 to 4. Furthermore, I have found that the extreme pressure properties of a sulfurand leadcontainingE. P. additive can be greatly enhanced and the atent O 2,175,558 Patented Dec. 25, 1956 of a minor amount of such a chlorinated fatty acid having from 12 to 30 carbon atoms per molecule. 5 t

In accordance with the present invention, lubricants comprising a mineral lubricating oil in the higher viscosity range, ordinarily employed in lubricants of this type, e. g., from about 40 to about 200 (S. S. U.) at 210 F. and preferably from about 7 5 toabout (S. S. U.) at 210 F., that is, lubricating oils of SAE #10 to SAE #60 grade, and containing as an E. P. component a sulfur-containing lead tallate or a lead soap such as lead naphthenate and a sulfurized fatty oil such as sulfurized sperm oil and also containing an effective amount of a chlorinated hydrocarbon such as a chlorinated parafiin wax may be rendered more effective by combining therewith a chlorinated fatty acid, such as 9,10-dichlorostearic acid in an amount of from about 1% to about 5% and preferably about 2% to about 4%. Such lubricants may also contain efiective quantities of various other typical lubricant additives such as antioxidants, detergents, etc. a j

The amount of sulfuncontaining lead tallate or lead naphthenate and sulfurized sperm oil as the lead and sulfur affording components of the combined additives in the extreme pressure lubricants of the present invention may vary over a relatively wide range depending on the end use of the lubricant, the lubricating oil employed, and the sulfur, lead and chlorine desired in the lubricant. In any event, the chlorinated fatty acid has been found to improve the E. P. propertiesof the sulfurized lead tallate containing from about 5% to about 30% by weight of lead and from about 5.0% to about 15% of sulfur, and also the E. P. properties of a lubricating oil in which the lead and sulfur additive components are not contributedlby a single additive such as sulfurized lead tallate. The chlorinated fatty acid, such as 9,10-chlorostearic acid is particularly useful in lubricants containing about 5% to about 15% of the sulfur-containing lead tallate resulting in lead content of finished lubricant of 0.5% to 5% lead.

The preferred sulfur-containing lead tallate'component is prepared and incorporated in the lubricating formulation according to the following procedure. Commercial grade tall oil is sulfurized with free sulfur, for example, flowers of sulfur to contain from about 5% to about 15%, preferably about 8% to about 10% by weight of sulfur by maintaining the tall oil at a temperature within the range of from about 300 F. to about 350 F. under conditions of efficient stirring over a period usually of about ten to fifteen hours during the first few hours of which period the sulfur is added incrementally. The reactionis completed to non-corrosiveness to copper. Thistest is applied by immersing in the product mixture a strip of copper, for a period of 10 minutes, temperature of the product being held at about 250 F. to determine corrosiveness to copper. Following sulfurization of the tall oil, the product is diluted with an equal weight of a hydrocarbon oil, for example, an aliquot of the lubricating stock of which the final additive is to become a part. To this diluted sulfur-containing tall oil is then added about 20% by weight of litharge based on the weight of the nondiluted sulfur-containing tall oil. The litharge is added slowly to the product and stirred at a temperature of 220 F. to 230 F. or it may be added as a slurry in an aliquot of the lubricating oil base stock. The reaction is complete when water is no longer evolved and the lead oxide has disappeared. The mixture is stirred at a temperature of about F. to about F. and the chlorinated hydrocarbon such as chlorinated parafiin wax and the chlorinated fatty acid are added as such or mixed with additional lubricating oil base stock following which the product is stirred to homogeneity and diluted with lubricating oil base stock to obtain the final composition desired. The 1ubricant, improved with respect to E. P.

properties, will consist essentially of the following .on a weight percent'basis:

Lubricating oil (10-60 SAE grade) 75-93 Sulfur-containing lead tallate -10 Chlorinated paraflin wax (40-70% C12) 1-10 Chlorinated fatty acid 1-5 To such a composition may be added from about 2 to 4 parts per million of a silicone antifoaming agent.

As indicated above, any commercial grade tall oil may be used as base stock for preparing the sulfur-containing lead tallate. The tall oil used in preparing the products describedbelow was Indusoil (double distilled) having the following properties:

Specific gravity--- 96-98 Viscosity at 210 F 42-62 Flash point -F 350-380 Acid No 180-185 Saponification No 181-186 Iodine No 170-180 Fatty acid, percent 61-66 Rosin, percent 30-33 This tall oil was obtained from Industrial Chemical Sales, Division of West Virginia Pulp and Paper Company.

When using lead naphthenate and Sulfurized sperm oil (which are available as commercial products) as the lead and sulfur affording materials the formation will contain from about 1.5% to about by weight of lead naphthenate, from about 2% to about 10% sulfurized sperm oil, from about 1% to about 10% of chlorinatedhydrocarbons such as chlorinated paraffin wax and from about 1% to about 5% ofa chlorinated fatty acid such as 9,10-dichlorostearic acid, the remaining component stock consisting essentially of the lubricating oil base stock. The lead naphthenate will usually contain about 25% or 30% lead and the Sulfurized sperm oil contains 10% to sulfur.

The chlorinated hydrocarbon, preferably chlorinated parafiin wax, may contain from about 40% to about 70% chlorine, preferably from about 40% to 55% chlorine. The range of chlorine content of 40% to about 55 is preferred primarily since these products of lower chlorine content range are liquid at ambient temperatures and hence can be added as liquids to the lubricating oil-diluted sulfur-containing lead tallate. The chlorinated wax products are known commercially as Chlorafins and are described by Kirk and Othmer in Encylopedia of Chemical Technology, vol. 3, pp. 781-785 (1949). The chlorinated paraffin wax used in the experiments described below was Chlorafin-42 obtained from Hercules Powder Company.

EXAMPLE I One thousand grams of tall oil were heated at a temperature of 300 F. to 320 F. over a period of 10 hours, during which period 100 grams of flowers of sulfur were added in. small increments. The sulfurized oil was noncorrosive to copper and contained 9.14% sulfur. his product was then diluted with an equal weight of Mid- Continent Base (acid-treated) SAE #10 grade oil and heated to a temperature of 220 .F. to 230 F. over a period of two hours, during which period 200 grams of litharge were added to the stirred mixture. The oildiluted sulfur-containing lead tallate product, which Was homogeneous, contained 9.7% lead and 4.15% sulfur. To 450 grams of this product was then added 120 grams of Chlorafin-42, that is, chlorinated paraflin wax containing 42% chlorine, and 120 grams of 9,10-dichlorostearic acid. Two thousand three hundred and ten grams of base'oih-that is acid-treated SAE #50 grade lubricating oil, was-added to this 690 grams of diluted composite additive to give an E. P. lubricant having the following composittion:

Percent by weight Sulfur-containing lead tallate 7.5 Chlorafin-42 4.0 9,10-dichlorostearic acid 4.0 Lubricating oil (SAE #10 grade) 7.5 Lubricating oil (SAE #50 grade) 77.0

EXAMPLE II A second composition was prepared according to the above procedure using the samples of the same sulfurcontaining lead tallate, Chlorafin-42, and 9,10-dichlorostearic acid which had the following composition:

Percent by weight Sulfur-containing lead tallate 7.5 Chlorafin-42 2.0 9,10-dichlorostearic acid 2.0 SAE #10 lubricating oil 7.5 SAE #50 lubricating oil 81.0

with 2 parts per million of silicone antifoaming agent added.

' EXAMPLE III A third composition was prepared according to the procedure outlined in Example I except that oleic acid was substituted for the 9,10-dichlorostearic acid component. A portion of the same sulfur-containing lead tallate and Chlorafin-42 were used. The composition of this formulation was:

Percent by weight Sulfurized lead tallate 7.5

Chlorafin-42 6.0 Oleic acid 4.0 SAE #10 (acid-treated) oil 7.5 SAE #50 (acid-treated) oil 75.0

with 2 parts per million of silicone antifoaming agent. This lubricant contained 1.01% sulfur, 0.96% lead, and 2.62% chlorine.

EXAMPLE IV An E. P. lubricant having the following composition was prepared:

' Percent by weight Lead naphthenate 5.0

Sulfurized sperm oil 5.0

Chlorafin-42 6.0

SAE #50 (acid-treated) oil 84.0

30% lead.

2 10-13% sulfur.

EXAMPLE V A formulation containing a commercial grade of basic lead naphthenate (30% lead), Sulfurized sperm oil, Chlorafin-42, and 9,10-dichlorostearic acid was prepared. This composition correspondedto the following formulation:

Percent by weight Lead naphthenate 5.0 Sulfurized sperm oil 5.0 Chlorafin-42 4.0 9,10-dichlorostearic acid 4.0 SAE #50 lubricating oil 82.0

This lubricant contained 1.04% sulfur, 1.53% lead, and 2.29% chlorine.

The load-carrying capacity of extreme pressure lubricants may be determined by extreme pressure testing machines, such as the Timken testing machine, described in the Journal of the Institute of Petroleum 32, pp. 209- 210 and 220-222 (1946). The mechanism and method of use of the machine is Well-known by those skilled in the art of testing petroleum products. In testing to determine the load a lubricant will carry, a test is made using a load the oil will carry readily and then successive tests are made using slightly increased loads until failure occurs. The results of the tests obtained in testing the formulations described in the above examples and of the base oil without E. P. additive are shown in the following table:

The superior extreme pressure properties of the formulation corresponding to Examples I and II which contained the 9,10-dichlorostearic acid component are evident from the results shown above. Although the formulation of Example IV contained 6% by weight of Chlorafin-42 as compared to 4% of Chlorafin-42 in Example I and 2% Ch1orafin-42 in Example II, the total percent of leadcontaining and sulfur-containing components was higher than in the single sulfur and lead containing tallate component of Examples I and II, the load-carrying property of the formulation of Example IV was not as pronounced as Examples I, II, and V. Comparing Example V with Example IV, it is noted that the use of 9,10-dichlorostearic acid in this combination of sulfur-containing and lead-containing additives also produced improved E. P. properties of the oil although the improvement was not as pronounced as in Example I. The load-carrying properties of the formulation represented by Example III is greatly improved by aging in a final heat-treatment step as described in my copending application entitled Extreme Pressure Lubricant, S. N. 453,435, filed August 31, 1954, now issued as U. S. Patent No. 2,726,209.

Having thus described my invention, I claim:

1. An extreme pressure lubricant consisting essentially of from about 75% to about 93% of a mineral lubricating oil, about 5% to about 10% of sulfur-containing lead tallate, from about 1% to about 10% of a chlorinated paraffin wax containing from about 40% to about 70% by weight of chlorine, and from about 1% to about 5% of 9, l0-dichl0rostearic acid.

2. The extreme pressure lubricant of claim 1 wherein the sulfur-containing lead tallate contains from about 5% to 15% by weight of sulfur and from about 5% to about 30% by weight of lead.

3. The extreme pressure lubricant of claim 1 wherein the chlorinated hydrocarbon is chlorinated paraffin wax containing from about 40% to about by weight of chlorine.

4. The extreme pressure lubricant of claim 1 wherein the sulfur-containing lead tallate contains about 20% by weight of lead and about 10% by weight of sulfur.

5. An extreme pressure lubricant consisting essentially of a petroleum lubricating oil base stock of viscosity within the range of about 40 seconds to about 200 seconds at 210 F. (SSU) in an amount of about 84.5% by weight, sulfur-containing lead tallate in an amount of about 7.5% by weight, a chlorinated paraflin wax containing from about 40% to about by weight of chlorine in an amount of about 4% by weight, and about 4% by weight of 9,10-dichlorostearic acid.

6. An extreme pressure lubricant consisting essentially of from about to about 93% of a mineral lubricating oil, about 5% to about 10% of sulfur-containing lead tallate, from about 1% to about 10% of a chlorinated paraffin wax containing from about 40% to about 70% by weight of chlorine and from about 1% to about 5% by weight of a chlorinated fatty acid corresponding to the general formula CnHZn-xClwOz Where n is an integer of value 12 to 30 and x is an integer of value from 1 to 4.

References Cited in the file of this patent UNITED STATES PATENTS Fainman Dec. 6, 1955 

1. AN EXTREME PRESSURE LUBRICANT CONSISTING ESSENTIALLY OF FROM ABOUT 75% TO ABOUT 93% OF A MINERAL LUBRICATING OIL, ABOUT 5% TO ABOUT 10% OF SULFUR-CONTAINING LEAD TALLATE, FROM ABOUT 1% TO ABOUT 10% OF A CHLORINATED PARAFFIN WAX CONTAINING FROM ABOUT 40% TO ABOUT 70% BY WEIGHT OF CHOLRINE, AND FROM ABOUT 1% TO ABOUT 5% OF 9,10-DICHLOROSTEARIC ACID. 